Cross-Origin Resource Sharing

This document defines a mechanism to enable client-side cross-origin requests. Specifications
that enable an API to make cross-origin requests to resources can use the algorithms
defined by this specification. If such an API is used on http://example.org resources,
a resource on http://hello-world.example can opt in using the mechanism described
by this specification (e.g., specifying Access-Control-Allow-Origin: http://example.org
as response header), which would allow that resource to be fetched cross-origin from
http://example.org.